Serology is a term used in forensics to describe testing methods that are typically used as a presumptive screen for the presence of specific biological fluids. Serological tests are typically antigen-antibody based or chemical reaction-based assays. The body fluids mostly commonly tested for in forensic casework are blood, saliva and semen, however, assays may also be conducted for urine and fecal matter in some cases.
For instance, if a bed sheet is collected from a crime scene where an alleged rape occurred, analysts must painstakingly screen the sheet for the presence of bodily fluids with potential investigative value. This is often achieved by combining the use of an Alternate Light Source (ALS) and serological testing to localize and presumptively characterize biological stains. Once potentially probative stains are collected, efforts are made to obtain a DNA profile.
There are a variety of tests available for the screening of different types of bodily fluids. Information on various serological tests as well as additional DNA testing techniques can be found in the links to the left.